Program Project support is requested for a coordinated, multidisciplinary approach to investigate the role of milk-borne hormones and other active biological substances for the neonate. Support is requested for three scientific projects and three cores (Morphological, Animal and Administrative). The three proposed projects deal with the fate and effects of milk-borne peptide hormones and carnitine in the suckling rat. They are: PROJECT 1. Role of Milk-Borne Growth Factors for the Suckling: Their Content and Synthesis. Principal Investigator: O. Koldovsky PROJECT 2. Role of Milk-Borne Growth Factors for the Suckling: Their Effects on the Neonate. Principal Investigator: A.F. Philipps PROJECT 3. Role of Milk-Borne Biological Substances in the Developing Liver. Principal Investigator: R. McCuskey These projects are basic in nature, and the information derived from them will be applicable to a variety of normal and pathological conditions. Studies have demonstrated that some of these substances are absent in infant formulas, but are present in human breast milk, emphasizing the important significance of these proposed studies.